/*
 * jPOS Project [http://jpos.org]
 * Copyright (C) 2000-2015 Alejandro P. Revilla
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.jpos.iso;

import java.io.IOException;
import java.io.InputStream;

/**
 * Uses a 2 EBCDIC byte length field.
 * <p/>
 * right-justified with leading 0
 * and packed data as BCD. 2 BCD digits
 * per byte and adding the value hex(0xF)
 * for padding if length is odd.
 *
 * @author julien.moebs@paybox.net
 * @author doronf@xor-t.com
 * @version $Id$
 * @see ISOFieldPackager
 * @see ISOComponent
 */
public class IFEB_LLNUM extends ISOFieldPackager {
	public IFEB_LLNUM() {
		super();
	}

	/**
	 * @param len         - field len
	 * @param description symbolic descrption
	 */
	public IFEB_LLNUM(int len, String description) {
		super(len, description);
	}

	/**
	 * @param c - a component
	 * @return packed component
	 * @throws ISOException
	 */
	public byte[] pack(ISOComponent c) throws ISOException {
		boolean odd = false;
		int len;
		String s = (String) c.getValue();

		if ((len = s.length()) > getLength() || len > 99)   // paranoia settings
			throw new ISOException(
					"invalid len " + len + " packing IFEB_LLNUM field " + c.getKey());

		// if odd length
		if (len % 2 == 1) {
			odd = true;
			len = len / 2 + 1;
		} else {
			odd = false;
			len = len / 2;
		}

		String fieldLength = ISOUtil.zeropad(Integer.toString(len), 2);

		byte[] EBCDIClength = ISOUtil.asciiToEbcdic(fieldLength);

		// bcd stuff
		byte[] bcd = ISOUtil.str2bcd(s, false);

		if (odd)
			bcd[len - 1] = (byte) (bcd[len - 1] | 0xf);

		byte[] b = new byte[bcd.length + 2];

		b[0] = EBCDIClength[0];
		b[1] = EBCDIClength[1];
		System.arraycopy(bcd, 0, b, 2, bcd.length);

		return b;
	}

	/**
	 * @param c      - the Component to unpack
	 * @param b      - binary image
	 * @param offset - starting offset within the binary image
	 * @return consumed bytes
	 * @throws ISOException
	 */
	public int unpack(ISOComponent c, byte[] b, int offset)
			throws ISOException {
		boolean pad = false;
		int len = (b[offset] & 0x0f) * 10 + (b[offset + 1] & 0x0f);
		int tempLen = len * 2;

		// odd handling
		byte lastByte = b[offset + 2 + len - 1];

		if ((lastByte & 0x0f) == 0x0f)
			tempLen--;

		c.setValue(ISOUtil.bcd2str(b, offset + 2, tempLen, pad));

		return len + 2;
	}

	/*
	 * code contributed by doronf@xor-t.com
	 */
	public void unpack(ISOComponent c, InputStream in)
			throws IOException, ISOException {
		byte[] b = readBytes(in, 2);
		int len =
				100 * (((b[0] >> 4 & 0x0F) > 0x09 ? 0 :
						b[0] >> 4 & 0x0F) * 10 + (b[0] & 0x0F))
						+ ((b[1] >> 4 & 0x0F) > 0x09 ? 0 :
						b[1] >> 4 & 0x0F) * 10 + (b[1] & 0x0F);
		c.setValue(ISOUtil.bcd2str(readBytes(in, len), 0, 2 * len, pad));
	}

	public int getMaxPackedLength() {
		return getLength() + 2;
	}
}
